Previous research suggests that an approach that includes a combination of acoustic and electrical stimulation within the same ear can be particularly effective for this group of hearing impaired listeners (von Ilberg et al., 1999;Gantz and Turner, 2003;Turner et al., 2008). This approach has been termed "Combined Electric and Acoustic (A+E) Hearing" and requires implantation of a Hybrid cochlear implant (CI). Preliminary results with the Hybrid CI have been very encouraging. Hybrid CI users can outperform traditional CI users on many tasks, including perception of music and speech in noise. While such results are promising, many important questions remain relative to the most appropriate signal processing techniques to use to combine the acoustic and electric stimuli. This study addresses a very specific goal: to determine how best to divide the acoustic speech spectrum between the acoustic and electric stimulation modes. We hypothesize that manipulation of this variable will have a significant effect on performance, and that understanding more about how to combine the acoustic and electrical signals within the same ear will lead to significantly improved levels of performance with the CI. We propose to systematically vary the way the hearing aid and/or cochlear implant are programmed and to assess the impact of those changes on performance. The specific changes in programming will include varying the range of frequencies allotted for acoustic and electric stimulation modes as well as the degree of overlap between the two frequency ranges. We propose to evaluate the effectiveness of these different approaches to programming the two devices using a range of both speech perception tests as well as a series of electrophysiologic measures that may be more applicable for difficult-to-test or pediatric populations. Hybrid CIs are a new technology that addresses a very significant need for a relatively large population. The proposed research will determine how best to approach fitting the two devices for individual hearing impaired listeners in order to maximize the effectiveness of this A+E technology in a relatively short time. PUBLIC HEALTH RELEVANCE: Well over 28 million Americans suffer from some degree of hearing loss. Many, because of the specific configuration of their hearing loss, have too much hearing to be considered for a cochlear implant but because of the configuration of their hearing loss, are not able to benefit from conventional hearing aids. These hearing impaired individuals struggle tremendously - particularly in noisy listening environments - and the impact on their lives and the public as a whole is significant. Preliminary research suggests that a new type of cochlear implant (CI), the Nucleus Hybrid CI, that is designed to preserve acoustic low frequency hearing while allowing high frequency components in speech or other environmental sounds to be processed electrically, can result in substantially improved hearing. Importantly, the ability of these listeners to continue to use their residual low frequency hearing to process acoustic signals and to combine that with electrical hearing in the same ear has resulted in significantly improved performance on tests that measure understanding of speech in background noise and enhanced perception of music. Currently, however, the number of individuals who use this technology is small. There is still a great deal that is not known about how these individuals will perform relative to patients who use a traditional CI and importantly, the best way to program the hearing aid and/or speech processor of the cochlear implant to optimize hearing abilities in this subject group has not been determined. That is the specific challenge this proposal seeks to address. The goal is to determine how best to divide the acoustic signal between the cochlear implant and the hearing aid. Outcome will be assessed using both behavioral as well as electrophysiologic methods that will be needed when the candidacy criteria for the Hybrid device is expanded to include pediatric or otherwise difficult-to-test populations. Such information can reasonably be collected within the two year time period of this grant and has the potential to dramatically accelerate the acceptance of this strategy by the medical community for this relatively large but previously underserved population.